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package org.glassfish.jersey.hk2;
import java.lang.reflect.ParameterizedType;
import java.lang.reflect.Type;
import java.util.IdentityHashMap;
import java.util.Map;
import java.util.function.Supplier;
import org.glassfish.jersey.internal.inject.DisposableSupplier;
import org.glassfish.hk2.api.Factory;
import org.glassfish.hk2.api.ServiceLocator;
import org.glassfish.hk2.utilities.reflection.ParameterizedTypeImpl;
/**
* This class is able to find the {@link Supplier} of the particular type and use this {@code Supplier} to create a new
* instance. If the {@code Supplier} is not found then {@code null} is returned.
*
* If the found {@code Supplier} is a type of {@link DisposableSupplier} then this bridge can delegate
* {@link Factory#dispose(Object)} invocation to {@link DisposableSupplier#dispose(Object)}.
*
* It's recommended to register the instance of this class as a singleton and then the {@link #provide()} is called according to
* a provided scope (for the created instance) during the binding process.
*
* @param type which could be handled by {@code Supplier} and this bridge.
*/
public class SupplierFactoryBridge implements Factory {
private ServiceLocator locator;
private ParameterizedType type;
private boolean disposable;
// This bridge can create multiple instances using the method 'provide' therefore must map created suppliers because of
// 'dispose' invocation later on.
// TODO: Key as a WeakReference - prevent objects in scope which never dispose the objects such as PerLookup.
private Map> disposableSuppliers = new IdentityHashMap<>();
/**
* Constructor for a new bridge.
*
* @param locator currently used locator, all factory invocations will be delegated to this locator.
* @param type generic type of a {@link Supplier} which is looked for in locator and on which the creation of
* the new instance is delegated.
* @param disposable flag whether the bridge is set up for disposing the created object.
*/
SupplierFactoryBridge(ServiceLocator locator, Type type, boolean disposable) {
this.locator = locator;
this.type = new ParameterizedTypeImpl(Supplier.class, type);
this.disposable = disposable;
}
@Override
@SuppressWarnings("unchecked")
public T provide() {
if (type != null) {
Supplier supplier = locator.getService(type);
T instance = supplier.get();
if (disposable) {
disposableSuppliers.put(instance, (DisposableSupplier) supplier);
}
return instance;
} else {
return null;
}
}
@Override
public void dispose(T instance) {
if (disposable) {
DisposableSupplier disposableSupplier = disposableSuppliers.get(instance);
disposableSupplier.dispose(instance);
disposableSuppliers.remove(instance);
}
}
}